Stihl ms-170 cord stuck (different?)

[pleasant]

CMR6H is the narrow 10mm plug that is fitted to the MS171 (and others) but NOT the MS170. That and the similar MS180 have the earlier old school engines fitted which DO take the larger (not longer) bpmr7a plugs, so I am confused as you said you have an MS170 not an MS171?? A cmr6h plug will not even fit in an MS170 hole as it will be too small in diameter. So doesn't make any sense I'm afraid.

 

Are your filler caps the white and black flip top ones or the all black screw down ones? Screw down means you have an MS170. Flip top means you have an MS171.

 

 

 

 

 

 

Edited June 20, 2023 by pleasant

[ScotiaMcBlurty]

Thanks Pleasant.  Re plug.  The online Stihl manual does say "NGK BPMR 7 A" but my hardcopy manual, which I still miraculously have, is defo "NGK CMR6H".  So I assume the design changed at some point.  Top of piston looks good from what I could see through the exhaust port.   

[pleasant]

OK. There may be a remote possibility you have an MS170 fitted with the 'eco' 2-mix engine, which for a limited time was fitted and that did take the CMR6H.

 

Not sure if your handbook is the same as this, but have a look at page 44 and you can see what I mean. Still doesn't help you with your issue, but at least answers why you may well have the CMR6H fitted.

 

https://www.godfreys.co.uk/wp-content/uploads/2021/02/0458-206-0121-B_ZBA_05_02.pdf

[ScotiaMcBlurty]

Hmmm ... thanks Pleasant, plot thickens. 

 

My manual says "STIHL MS 170" on the cover.  Its only for the MS 170, no other guidance for any other model is provided (each page says MS 170).    Its 44 pages long, and page 44 is blank.  Copyright statement is "ANDREAS STIHL AG & Co KG, 2013".   Picture of the Engine Spec page is attached... strange one this.

[ScotiaMcBlurty]

Filler caps are both black, screw down.  Plug hole is 10mm diameter.  My engine output is also slightly different to the manual you posted (I only have 1.6HP).

 

Can only assume for some limited time period they used this plug in the MS 170, right? 

[openspaceman]

5 hours ago, ScotiaMcBlurty said:

Which does make sense, as even if I just cover the hole with my finger, the cord still goes tight. 

Just a wild thought; have you checked the starter pulley for cracks.

 

A long time ago, and I can no longer remember which saw, I had a saw that you could pull over slowly but when you tried to start it the pulley would jam. What was happening was that as soon as the cord met some resistance  it would sink beside the next turn and because the pulley was cracked around the boss the pulley sides were forced out and jammed against the starter cover.

[Bill C]

Take the starter pulley case off(bit of a fiddle) and check the flywheel isn't loose and see if you can turn the engine by hand.

[ScotiaMcBlurty]

Gave it an oil bath last night ... then left it to drain out overnight.  Cord does seem a little better (or maybe its wishful thinking!), but not free enough to start.  So will have a look at the pulley tonight as well - at least remove that variable from the equation.  If nothing else, I'll learn more about how it works ... but I fear a trip to Honey Brothers (dealer) might yet be on the cards.     Cheers all.

[pleasant]

Without wishing to appear demeaning, but taking a 7 year old ms170 worth probably 50 quid to a dealer is simply going to prove its beyond an economical repair for them to look at it. I try as be as tactful as I can with customers in the same situation...particularly those that ask 'is it worth repairing?'. We charge a 30 quid estimate/inspection fee upfront. That way we dont work for nothing and the customer doesnt end up with a bill they dont want to pay. Allows us to assess the machine price the job and contact customer. We do have customers with cheaper or older machines that 'baulk' at the suggestion we want the 30 quid to look at it......to which i simply say 'if you dont want to pay 30 quid for us to find out whats wrong with it, then you certainly wont want to pay more for us to repair it.....to that end you've just made your decision whether its worth repairing'

 

 

Edited June 21, 2023 by pleasant

[openspaceman]

2 hours ago, ScotiaMcBlurty said:

but I fear a trip to Honey Brothers (dealer) might yet be on the cards. 

as pleasant says; likley to be uneconomic. I am less than ten miles north of Honey Bros and could take a look